The overall objective of the proposed research is to generate a profile of the effects on complex behavioral processes of four narcotic drugs which are either abused by or are administered on a chronic basis to humans. Specifically, the effects of heroin, LAAM, methadone and morphine on complex operant tasks involving learning and memory in nonhuman primates will be the major focus of investigation. The technique of repeated acquisition will be used to study the effects of each of these drugs on learning, with and without added stimuli, in primates under two different baseline conditions. Multiple schedules will be used in order to make a direct comparison of drug effects on the acquisition and performance of complex discriminations. A delayed matching-to-sample procedure will be used to evaluate drug effects on short-term memory. The major research effort will concentrate on the following experiments with primates. Acute dose-effect data will be obtained for heroin, LAAM, methadone, and morphine under each baseline. The specificity and degree to which naloxone and naltrexone will antagonize the behavioral effects of each of these drugs on learning, performance, and short-term memory will also be determined. Finally, the behavioral effects of chronic heroin administration and the extent o cross-tolerance to LAAM and methadone will be investigated under each baseline.